code: def convert_postfix_list(arr, i=0):
      if i >= len(arr):
          raise LaTeXParsingError("Index out of bounds")
  
      res = convert_postfix(arr[i])
      if isinstance(res, sympy.Expr):
          if i == len(arr) - 1:
              return res  # nothing to multiply by
          else:
              if i > 0:
                  left = convert_postfix(arr[i - 1])
                  right = convert_postfix(arr[i + 1])
                  if isinstance(left, sympy.Expr) and isinstance(
                      right, sympy.Expr
                  ):
                      left_syms = convert_postfix(arr[i - 1]).atoms(
                          sympy.Symbol
                      )
                      right_syms = convert_postfix(arr[i + 1]).atoms(
                          sympy.Symbol
                      )
                      # if the left and right sides contain no variables and the
                      # symbol in between is 'x', treat as multiplication.
                      if (
                          not (left_syms or right_syms)
                          and str(res) == "x"
                      ):
                          return convert_postfix_list(arr, i + 1)
              # multiply by next
              return sympy.Mul(
                  res, convert_postfix_list(arr, i + 1), evaluate=False
              )
      else:  # must be derivative
          wrt = res[0]
          if i == len(arr) - 1:
              raise LaTeXParsingError(
                  "Expected expression for derivative"
              )
          else:
              expr = convert_postfix_list(arr, i + 1)
              return sympy.Derivative(expr, wrt)
  
imports: from importlib.metadata import version
  import sympy
  from sympy.external import import_module
  from sympy.printing.str import StrPrinter
  from sympy.physics.quantum.state import Bra, Ket
  from .errors import LaTeXParsingError
label_desc: Use image node_id 7 for calling a global function with example usage: convert_postfix_list(arr, i) and returns: res, sympy, sympy, convert_postfix_list